The present invention relates to unsaturated polycyclic esters, and particularly to unsaturated polycyclic ester monomers, which are suitable for polymer synthesis producing polymers having good hydrophilicity, adhesion and dry-etch resistance.
Integral circuit layering is crucial in semiconductor industries such that the number of integral layers on an integral circuit must be maximized. Therefore, narrower wire widths for lithography are required. To achieve better resolution, light sources with shorter wavelengths or exposure systems with larger numerical apertures are applied.
Recently, a polymer suitable for the 193 nm wavelength light source was developed, which is a copolymer formed by four kinds of monomers and named iBMA-MMA-tBMA-MMA (poly isobornyl methacrylate-methyl methacrylate-t-butyl methacrylate-methacrylic acid). The structure of this polymer is as follows: 
For such polymers, there are still some disadvantages, for example, low etch resistance and bad adhesion due to the four monomer composition. Therefore, if producing photoresist compositions with this polymer, creating a new process becomes necessary.
U.S. Pat. Nos. 6,271,412 and 6,280,898 and Japanese Patent Publication No. 2001-242627 have disclosed different monomers for synthesizing photosensitive polymers, which can form photoresist compositions and then be applied to semiconductor component manufacturing.
The object of the present invention is to provide unsaturated polycyclic ester monomers, which are suitable for synthesizing polymers having good hydrophilicity, adhesion and dry-etch resistance, or reacting with one or more unsaturated species to form polymers or copolymers.
The compound of the present invention has the following structure (formula I), 
wherein R1 is H, haloalkyl group or C1-C4 alkyl group; R2 is hydroxyl group, C1-C8 alkoxy group or C1-C8 thioalkyl group; G is (CH2)n, O or S, wherein n is 0, 1, 2, 3 or 4; Rc is a lactone group; and m is 1, 2 or 3.
When a proper catalyst is added, formula (I) can form polymers or copolymers through polymerization or copolymerization with other vinyl monomers.
Furthermore, these polymers or copolymers can form chemical amplified photoresist compositions with photo-acid generators (PAG), additives and solvents. These compositions can then be applied to general lithography processes, and particularly to ArF, KrF or the like processes to obtain superior resolution, and photosensitivity.
The present invention provides a compound of the formula (I), 
wherein R1 is H, haloalkyl group or C1-C4 alkyl group; R2 is hydroxyl group, C1-C8 alkoxy group or C1-C8 thioalkyl group; G is (CH2)n, O or S, wherein n is 0, 1, 2, 3 or 4; Rc is a lactone group; and m is 1, 2 or 3.
The formula (I) compound of the present invention can be synthesized by the following steps: 
wherein R1, R2 and G are defined as the above.
In Step 1, a proper diene compound such as butadiene, cyclopentadiene, furan and thiophene, reacts with maleic anhydride to perform the Diels-Alder reaction. Then, the acid anhydride adducts are reduced under the well-known conditions in the second Step 2. Preferably reaction is carried out using sodium boron hydride in dried polar solvent such as dimethylformamide or tetrahydrofuran. In Step 3, peroxide is provided to oxidize the double-bond compound into an epoxide. In Step 4, the epoxide reacts with a proper nucleophilic reagent such as water, alcohol and thiol, to perform a ring opening addition reaction under an acidic environment obtaining a hydroxyl derivative. In Step 5, the hydroxyl derivative reacts with (alkyl)acryloyl chloride or acryloyl chloride to perform esterification resulting in the compound of formula (I). Detailed procedures for preparing the compound of the present invention are described in the preferred embodiments.
By polymerizing the compound of formula (I), polymers with repeated units can be obtained, which has the following structure formula (II), 
wherein R1 is H, haloalkyl group or C1-C4 alkyl group; R2 is hydroxyl group, C1-C8 alkoxy group or C1-C8 thioalkyl group; G is (CH2)n, O or S, wherein n is 0, 1, 2, 3 or 4; Rc is a lactone group; and m is 1, 2 or 3.
The compounds of formula (I) can be polymerized or copolymerized with other vinyl monomers to produce various polymers with or without the assistance of catalysts. Particularly, when applied to 193 nm processes, the vinyl monomers preferably have no aryl group to enable light to pass through. The following examples illustrate some of the vinyl monomers, wherein R3 is H, haloalkyl group or C1-C4 alkyl group. 
By reacting the compound, formula (I), with one or more of the above vinyl monomers, the polymers can be prepared. These polymers are suitable for producing chemically amplified photoresist compositions that can be applied to general lithography processes, and particularly to ArF, KrF or the like processes.
More detailed examples are used to illustrate the present invention, and these examples are used to explain the present invention. The examples below, which are given simply by way of illustration, must not be taken to limit the scope of the invention.